U.S. Pat. No. 3,871,337 and GB 1 578 644 disclose 4-stroke internal combustion engines. In both cases the engines are equipped with a rotor part which is rotatable in a circular cavity in the motor casing about an axis which is arranged concentrically to the motor casing's main axis.
In U.S. Pat. No. 3,871,337 four working chambers are illustrated, the extent of each being limited in a 90 degree area within the rotor part's radial dimension in the motor casing. The working chambers are subjected in turn to each of their four strokes in the internal combustion engine. In each working chamber there works a piston in the form of a flat plate part, each of which is hinged to the rotor part. The plate parts are each subjected to forcible swiveling movement forwards and backwards in a limited area in their related working chamber in the rotor part.
GB 1 578 644 illustrates a motor of a similar kind, provided with six working chambers.
The motor according to the invention involves an expansion motor, i.e. a simple single stroke motor, driven by pressure supplied by a pressure medium such as gas, air, steam or hydraulics. By means of a piston the rotor part is set in rotation, generating motive power from an outgoing drive shaft in extension of the rotor part. In a known per se manner the rotor part is rotatable about an axis that is eccentrically located in the motor casing, thus enabling the rotor part in a restricted area on the rotor part's periphery to form rotating sealing abutment against the motor casing's inner wall, while remaining areas of the rotor's periphery are uncovered against the remaining cavity that forms the actual working chamber. The piston divides the disposable working chamber into a pressure chamber and a discharge chamber by means of the said piston.
NO 107 036 illustrates a single stroke motor with a cylindrical cavity and a rotor part that is eccentrically mounted in a related cavity. The rotor part carries a piston-forming plate part, which by means of a pressure spring is pushed in the rotor's radial direction to sliding support abutment against the cavity's peripheral wall. As a result of the use of a radially movable, piston-forming plate part in the rotor part, the rotor part necessarily occupies a large portion of the motor casing's cavity, with the result that the volume of the working chamber is severely limited with correspondingly limited ability for axial movement for the piston-forming plate part.
WO 03/012259 discloses a single stroke motor with a non-cylindrical cavity in the motor casing. In the motor casing a cylindrical rotor part is rotatably mounted which forms the motor's piston and which is provided with rotational power from applied pressure medium. In addition, in the motor casing one end of a plate part is pivot-mounted, which is arranged to be pivoted with the opposite end inwards towards the rotor part in order to form a sealing abutment against the rotating rotor part, controlled by the pressure force in the pressure medium. The plate part is curved in the longitudinal direction, thus enabling it when pivoting backwards and forwards in the motor casing's cavity to form sliding sealing abutment against the rotor part. The plate part uncovers and covers a radially outer port opening for supply of pressure medium to the motor's pressure chamber, while the rotor part similarly covers and uncovers a radially inwardly located port opening for draining discharge medium from the discharge chamber. With its cylindrical peripheral surface, the piston-forming rotor part, which is cylindrical in shape, provides poor utilisation of the energy supplied to the motor. In addition, the solution requires a working chamber with a complicated shape, i.e. an approximate figure-of-eight shape. Moreover, the relatively large dimensions employed for the rotor part and for the plate part provide a relatively poor utilisation of the working chamber's volume.
The object of the present invention is to provide a simpler and more efficient solution than that derived from WO 03/012259, which represents the most obvious state of the art.